Recovery of organic oxygenated compounds from hydrocarbon oils



Nov. 22, 1955 H. J. HIBSHMAN RECOVERY OF ORGANIC OXYGENATED COMPOUNDSFROM HYDROCARBON OILS Filed Aug. 21, 1952 3 (lttorneg M t n wm .zu onmohudahxu :2 H PIG .ru m.u 3 cm vm 1 n \NN wN Q -ow .m mma aim A|| mmL Ma A QN m v r mohu-Qhxu QM 9 mumnamum chm Iv G i wimmau NV p WE N nwmmQoFu u A RECOVERY OF ORGANIC OXYGENATED COM- POUNDS FROM HYDROCARBONOILS Henry J. Hibshman, Plainfield, N. J., assignor to Esso Research andEngineering Company, a corporation of Delaware This application is acontinuation-in-part of Serial Number 791,592 filed December 13, 1947,now U. S. Patout No. 2,626, 276, granted January 20, 195 3.

The present invention is concerned with the recovery ofoxygen-containing organic compounds from mixtures thereof withhydrocarbon oils, particularly with hydrocarbon oils of substantiallythe same boiling range, by a process involving extraction with sulfurdioxide in conjunction with a high boiling Wash solvent insoluble insulfur dioxide.

Various processes are known to the art in which a mixture ofhydrocarbons and organic oxygen-containing compounds are produced. Someof these processes are the low temperature carbonization of coal, peatand similar materials, destructive hydrogenation of coals, wood andshales, the methanol synthesis, the x0 synthesis in which olefins arereacted in the presence of carbon monoxide and hydrogen, and numerousoxidation processes, particularly the oxidation of propane and ofpetroleum oil fractions such as is described in Ellis Chemistry ofPetroleum Derivatives, vol. 1, chapter 36, pages 830 to 845. Thisinvention is also particularly applicable to products resulting from thehydrocarbon synthesis process whereby hydrogen and oxides of carbonarereacted in the presence of a catalyst to produce synthetichydrocarbons, water and numerous organic oxygenated compounds. Theoxygen-containing compounds producedin this synthesisoporation may be amajor product or a relatively small byproduct depending upontheoperating conditions. These oxygenated materials are extremelyvaluable as chemicals. Normally they consist of a mixture of alcohols,acids, aldehydes, ketones and esters. They are, however, difiicult toseparate from the hydrocarbon oil because they (1) are so numerous, 2)boil within the same range as the hydrocarbon oils and, in addition, (3)often form azeot ropes with each other and with the hydrocarbon oils.

Normally when the products of the above-described synthesis operationare condensed and allowed to settle the condensate separates into aell-phase system, that is, an upper oil layer comprising substantiallyhydrocarbons and hydrocarbon-soluble materialsand a lower water phasecomprising substantially water and water-soluble materials. Theoxygen-containing organic compounds formed in the synthesis operationrange from very low molecular weight compounds to very high molecularweight compounds and therefore, find themselves distributedthroughontthe oil phase and the water phase, the proportion in eachphase depending on their solubilities in the respective phases. Ingeneral, it can be said that the bulk of the organic oxygen-containingcompounds of one to four carbon atoms will enter the aqueous phase whilethe bulk of the compounds containing 5 carbon atoms and above permolecule will be found in the oil layer, although it should be borne inmind that the separation of materials into their respective phases isoftentimes not clean-cut and depends to alarge extent upon theconditions involved and the over-all composition of the materials in thecondensate. In general, a better separaa United States Patent 0 tion isobtained with the compounds containing 1, 2, and 3 carbon atoms, andthose containing 7 and more carbon atoms per molecule; the l, 2 and 3carbon atom molecules going principally into the water phase, while themolecules containing 7 or more carbon atoms go principally into the oil.The compounds containing 4-, 5 and 6 carbon atoms per molecule are ingeneral split between the two phases.

l n this invention, we are concerned with the separation and recovery inone operation of all the organic oxygencontaining compounds such asalcohols, acids, esters, aldehydes, ketones, etc, from their mixtures:with hydrocarhon oils. The invention is particularly applicable to theproducts resulting from the previously mentioned hydrocarbon synthesisreaction Whereby hydrogen and oxides of carbon are reacted in thepresence of catalysts. According to the process of this invention themixture of oxygen-containing compounds and hydrocarbon oils is extractedwith sulfur dioxide in conjunction with a wash solvent insoluble insulfur dioxide, preferably in a countercurrent operation and tractionwhereby the ox gen-containing compounds dissolve in the sulfur dioxideforming the extract phase, leaving the raffinate phase composedsubstantially of the hydrocarbons and the wash solvent.

The material subjected to extraction, according to the terms of thisinvention, is complex in nature. posed of hydrocarbons includingparafiins, olefins and in some cases, small amounts of aromatics. Inaddition, it contains anywhere up to about50% or more ofoxygencontaining aliphatic compounds such as alcohols, acids, esters,ketones, aldehydes, and condensation products thereof. In cases wherethe material is hydrocarbon synthesis operation, the oil will havedissolved in its certain proportions of each, alcohols, acids,

aldehydes, ketones and esters. The esters predominate among the highboiling compounds, particularly that fraction boiling above 350 that is,aldehydes and ketones, acids and alcohols, predominate among theoxygen-containing compounds boiling at temperatures up to about 350 F.The acid concentration reaches a maximum (20%) in the intermediate range(275 F. to 400 F.) several fold higher than at either extreme (S to 6%).Ordinarily the amounts of alcohols and acids found decrease withincreasing temperatures due undoubtedly to the fact that they undergoesterification reactions. The oxygen content of the total hydrocarbonoils resulting from the synthesis operation, i. e. oil layer plus waterlayer, generally run from 5 wt. percent to 20 wt. percent.

The process of the invention involves the extraction ofoxygen-containing compounds from mixtures thereof with hydrocarbon oils,particularly those within substantially the same boiling range as theoxygen-containing compounds by contacting the mixture with sulfurdioxide i in conjunction with a sulfur dioxide-insoluble wash solvent,preferably in a countercurrent liquid-liquid extraction operation. Ithas been found that an extract is formed containing to of theoxygen-containing compounds contained in the mixture. The hydrocarbonsremain in the rafiinate phase. In the extraction the sulfurdioxide-insoluble Wash solvent is introduced at least in part at the endof the extraction zone from which the sulfur dioxide extract iswithdrawn. If desired, wash solvent may also be introduced atintermediate points in the extraction zone or it may be added at leastin part with the feed stock. In this feature of the invention, the

less sulfur dioxide-soluble components are concentrated in the washsolvent and the more sulfur dioxide-soluble components remain in thesolvent. When this washing is carried out in a countercurrent manner,contamination of the more sulfur dioxide-soluble components in thepreferably in a liquid-liquid ex It is com derived from the F. whilecarbonyl compounds,

from the scrubber 13 are removed by line 16 and are processed forfurther recovery of hydrocarbon and oxy compounds therefrom. Thus, it isseen that the feed to extractor can be either (1) the oil layerresulting from the synthesis condensate, (2) the .oil layer plus thescrubbed water layer or (3) the scrubbed total gaseous effiuent from thesynthesis reactor; the scrubbing agent in each instance being at least aportion of the wash solvent to be employed in the subsequent extractionstep. As indicated before, the sulfur dioxide extraction step canfrequently be made more effective by treating the extraction feed withwater. This can be done by passing the hydrocarbon layer from separator8 to scrubber 40 where it is contacted with water introduced throughline 42. The water thus washes out the water soluble oxygen compoundswhich are then withdrawn as an aqueous phase through line 43 while thescrubbed hydrocarbon phase is withdrawn via line 41 and passed toextractor 10 via line 11. t v

Returning now to extractor 10, the mixture of hydrocarbon oil and oxycompounds enters either through line 11 or through line 9 or through anumber of split feed lines. However, preferably the feed is added at apoint near or below the midpoint of the extractor 10. In the event thatthe feed to the extractor has not previously with or withoutfractionation by distillation of the diverted portion from stripper 22and led via line 28 to extractor 29 entering at a point near or belowthe midsection thereof. In the extractor 29, the extract prior toremoval of S02 therefrom, is treated countercurrently with a secondportion of S02 entering through line and a second portion of washsolvent entering through line 31. The secondary extract containing ahigher proportion of aromatic hydrocarbons and olefinic hydrocarbons, isremoved from the extractor via line 32 and can be processed for recoveryof valuable aromatic and olefinic material therefrom. The secondaryraftinate is removed from extractor 29 via line 33 and is led tostripper 22 for recovery of oxy compounds therefrom as previouslydescribed. When such a modification is employed, it should be readilyunderstood that the bottoms emerging from stripper 22 via line 24 willhave to be treated by fractionation, solvent extraction, or othermethods to separate the oxy compounds from the wash solvent.

Various runs have been made to demonstrate the selec- S02 SELECTIVITYFOR OXY COMPOUNDS l Wt. percent feed component plus wash solvent inextract phase.

2 Beta=Wt. ratio oxy compound/hydrocarbon in extract/wt. ratio oxycompound/hydrocarbon in raflinate (solvent and wash solvent free basis).

been scrubbed with the wash solvent, wash solvent is added to the feedthrough line 17 or to the extractor through lines 18 and 9. Liquidsulfur dioxide enters the top of the extractor through line 19.Countercurrent flow of sulfurdioxide, the feed and the wash solvent,occurs in the extractor and the sulfur dioxide extract containingoxygen-containing compounds dissolved from the feed is withdrawn fromthe bottom of the extraction zone via line 20. The raffinate consistingsubstantially of the washsolvent and the hydrocarbon oil is withdrawnfromythe extractor through line 21. The extract is led to stripper 22for removal therefrom of sulfur dioxide via line 23 for return to feedline 19. The bottoms from the stripper 22 consist of oxygen-containingcompounds and small amounts of wash solvent and the mixture is removedvia line 24 and treated for recovery of theoxy compounds therefrom bysuch known means as fractionation, solvent extraction, extractivedistillation, or other desirable means not shown. The raftinate is ledto stripper 25 from which sulfur dioxide is distilled 01f and returnedvia line 26 to feed line 19. Bottoms from the stripper consistsubstantially of hydrocarbons and wash solvent and are removed via line27 for separation, such as by fractionation, solvent extraction, ex-

tractive distillation, or other desirable means not shown in thedrawing.

In the event that the sulfur dioxide extract being removed from. theextractor via line 20 contains material such as aromatic hydrocarbonsand some low boiling olefinic hydrocarbons which are more readilyextracted from the feed by sulfur dioxide than theoxygen-containingtcompounds, the extract is wholly or partly divertedThe results of these and other studies indicate that the capacities ofsulfur dioxide for the oxygen-containing compounds increases with themolecular weight of the oxygen-containing compound. Experimental resultsalso indicate that sulfur dioxide has extremely good extraction capacityfor oxygen-containing compounds of different chemical types and thatthis capacity is greatest for esters and acids.

A particularly significant feature of the effectiveness of sulfurdioxide as a solvent for the particular extraction process of thisinvention is the very high capacity of sulfur dioxide for extractingpractically all of the oxygen-containing compounds regardless of theirchemical nature in a single extraction. This feature is of considerablepractical and commercial interest since no other solvent has beenreported capable of performing this particular function.

A number of extractions have been made to recover oxygen-containingcompounds from hydrocarbon oils prepared in a hydrocarbon synthesisoperation. The feed stock employed in these extractions was a syntheticoil (particularly a fraction from which the material boiling below 200F. had been removed) prepared by reacting hydrogen with carbon oxides inthe presence of a sintered red iron oxide catalyst promoted withpotassium carbonate. These extractions were carried out in continuouscountercurrent operation employing sulfur dioxide in a 2 in. innerdiameter tower 23 ft. high, packed with Raschig rings under a 600-900 F.initial boiling point parafiinic white oil as a wash solvent. Data fromthese runs are listed in the following table:

Examp e I Top Bottom m Oxygon Content, Wt. Percent 7 OJ, gen Compounds,Wt. Percent"; man a Oxygen Content, Wt. Percent. Oxygen Gornpounds, Wt.Percent The wash solvent treats were purposely high to help compensatefor the insuflicient stage equivalents of the tower. Low temperatures atwhich somewhat higher select ivities rnightbe realized were notemployedin order to avoid the use of refrigeration and secondly toprevent precipitation of waxy materials which would occur even he resslne th e ye s The rafiinate compositions indicate that good removalof the oxygen-containing compounds from the raffinate is obtained whensomewhat higher than theoretical. extraction yields are taken.Similarly, high extract purities are indicated under conditionsresulting in some loss of oxygen-containing compounds in the raiiinate.High extract oxygemcontaining. compound purities were obtained in the350 to 5 4)? F. boiling range which ishighly significant sinceextractionof thismaterial. with many other solvents is impossible or at bestdifficul t.

T he oxygen-containing compound; distribution in the extract accordingto boiling point and chemical type (on a hydrocarbon-free basis) isshown in thef ollowing table forRun #1 which is typical of thedistribution found in all cases.

TYPICAL MP UND DISTRIB TION [Fraction analyzed: Extract of zoo-550 F.boiling range (29 wt. percent yield on ZOO-550 F. traction of feed toextraction; 56.8 vol. percent of the original synthesis oil was in thisboiling range) Fraction P l t 5/1 R.) Analysis %i;r1;iil[ll:dExtract-.

Wt. Percent (Hydrocarbon-Free Yield, Basis) Boiling Range, F. Volt.

' Pe cent. Gab

Esters Alcohols bonyls Acids Estersand carbonylspredominate in the highand low boiling ranges respectively. The proportion of estersincreasesseveral fold (80%) asthe boiling range goes from.200 to. 550 F. whilethe carbonyl contentstarts out high.andundergoesroughly a LO-folddecrease (SO-5%). Aseveraljold increase in acidconcentration occurs inthe interrncdiate.boilingrange (NS-490 F.). The alCOhQls how. ate s e cyt reach max m te era t". r c l tev Pain 5 t: t 21. The high ester.contents. of these fractions is too large degree attributabletoreactionot acids andalcohols duifing distillat n before or after S02extraction.

1a., 300- F., and 475 F.

It n. R n hat he .e re en res s are consiste t.

A limit on extract olefinichydrocarbons.

. in the center stage.

. 8 the feed which is more readily extracted than, groom-f pounds, suchas aromatic hydrocarbons and low bo' By the extraction process outlined,extract purities of 76 to 95% weight oxygen-containing compounds iron;fractions both relatively rich and relatively lean in oxygen-containingcompounds are obtainable. The use of}; higher extraction tower orincreased number of stages would permit even, a more complete recoveryat considerably higher concentration of' oxygen-containing oompounds(feeds richer in oxygen) 'with lower solvent re t n. ge r ulfu d e' x rfl Qt yd c r bori oils will eifect about 7 51-85% recovery and purityoi; y e i nt ins e maqqnd when u ing 3 st rts at 30.0500 lumepere n't,re an b u 9. E F a v p y o x e -c nta ning. c m un s. hen. igs. 9, ge t2 vol m per ent treat- Example 11 hesi a contain ng 8 tx sg PI QQW- w eintst izwwr m tse r on. ox de a The. xtracti n. es slc a 14- E- usi eat.Qt 4 11x 1. 1% S02 and 470 vol. Marcol (white oil, boiling point 500-800F.) wash solvent with the feed stock introduced A 59 vol. raifinatehydrocarbon concentrate containing 1.5 wt. oxygen was obtained. Thisraflinate oxygen concentration corresponds to 10% of the. oxygen in theoriginal feed or to a recovery of 90% of the oxygen in the extract. Thedistribution according to chemical type of oxy-compounds found in theextract is given in the following table:

Feed; Stock: 200-550 F. HCS O11 produced with sintered K200; promotedred iron oxide catalyst.

Extraction Conditions (Run 0-2): Temperature, +l4 F. S01 Treat, 481

vol; pbrpent; Marcol treat, 470 vol. percent; Feed to Center Stage.

Extract Fraction (15 Plate, 5/1 RR.)

' Wt. Percent Boiling Range F. g ig pounds nut-132 3.2 182-228 12. 7 63.9* 9'. 5' .0-3.

Esters account for the largest volume ofoxy-compoundsin all but thefirst extract cut. Carbonyls ('aldehydes; and ketones) arenextinabundancewith acids and alcohols in lesser abundance. Thepreponderanceof esters is attributable to esterification of the originalalcohols: and acids during distillation; they could be converted thewhite oil wash. Withoutthe contamination, the-trend. of increasingpuritywithboiling rangecan.be continued,

producing a 500-600 F; fraction or purity. The purities ofall fractionsmay be improved a lower extract yield:

In connection with the extraction processemployingsulfur. dioxidewiththe hydrocarbon oxygenated-c pound mixturesmentioned, itis-significant thatno u ficultyhas been experienced with respect= toreacti of sulfurdioxide with materials; present in rem step. Sulfurcontents: of the rafli'nate and' extract various runs ranged. from 0.043to 0.12% r v by taking indicating that reactivity of sulfur dioxide doesnot present a serious problem in the process of this invention.

The nature of the extraction process of the present invention and itspractical applications are evident from the preceding specification,drawing and data presented although it is not intended to unduly limitthe generally broad scope of the invention thereto.

What is claimed is:

1. An improved process for the separation of hydro carbons andoxygenated compounds produced by the catalytic hydrogenation of oxidesof carbon which coinprises, condensing and cooling the products of thehydrogenation whereby a water layer and an oil. layer are produced,separating the layers, washing the water layer with asulfur-dioxide-insoluble substantially non-aromatic hydrocarbon wash oilto form an absorbate containing hydrocarbons and oxygenatedcornpounds,introducing the absorbate and oil layer into an extraction zone,introducing sulfur dioxide into the extraction Zone, removing from theextraction zone an extract phase containing the oxygenated compounds anda raffinate phase containing the hydrocarbons produced by thehydrogenation reaction and the wash oil and recovering the oxygenatedcompounds from the extract phase.

2. A process according to claim 1 in which the substantially nonaromatic hydrocarbon is a white oil boiling in the range of 300 F. andhigher.

10 '3. A process according to claim 2 in which the white oil boils inthe range of 500 F. and 900 F.

4. A process according to claim 1 in which the hydrocarbon is ahydrocarbon oil formed in the hydrogenation reaction and boiling in therange of 300 F.700 F.

5. A process according to claim 1 in which the nonaromatic hydrocarbonis pentane and in which the extract with S02 is carried out at atemperature between the limits of F. and F.

6. A process according to claim 1 in which the said oil layer is Washedwith water to remove therefrom Water-soluble oxygenated compounds priorto extraction with S02.

7. A process according to claim 1 in which additional wash oil isintroduced into the extraction zone at the end from which the S02extract phase is withdrawn.

References Cited in the file of this patent UNITED STATES PATENTS1,838,547 Haslam et a1. Dec. 29, 1931 2,405,660 Linn Aug. 13, 194-62,505,752 Burton May 2, 1950 2,605,276 Bruner et a1. July 29, 19522,626,276 Hibshman Jan. 30, 1953 FOREIGN PATENTS 661,916 Great BritainNov. 28, 1951

1. AN IMPROVED PROCESS FOR THE SEPARATION OF HYDROCARBONS AND OXYGENATEDCOMPOUNDS PRODUCED BY THE CATALYTIC HYDROGENATION OF OXIDES OF CARBONWHICH COMPRISES, CONDENSING AND COOLING THE PRODUCTS OF THEHYDROGENATION WHEREBY A WATER LAYER AND AN OIL LAYER ARE PRODUCED,SEPARATING THE LAYERS, WASHING THE WATER LAYER WITH ASULFUR-DIOXIDE-INSOLUBLE SUBSTANTIALLY NON-AROMATIC HYDROCARBON WASH OILTO FORM AN ABSORBATE CONTAINING HYDROCARBONS AND OXYGENATED COMPOUNDS,INTRO-